The gas that provides millions of schoolchildren with hours of fun and gives stink bombs their revolting smell could soon provide doctors with new treatments for conditions ranging from strokes to chronic arthritis.

Some researchers are even trying to use hydrogen sulphide - the source of rotten eggs' unpleasant odour - to put patients with strokes or serious injuries into a form of suspended animation to help them survive severe traumas. This research is now being backed by the US military, who believe it could help their surgeons cope with injuries suffered by soldiers in battle.

'Hydrogen sulphide is made in very low doses in the body and, far from doing harm, it has become clear that it can do a great deal of good,' said Dr John Wallace, a pharmacologist at the University of Calgary in Canada. 'It is found in the brain and is also thought to control blood pressure. It is quite pervasive, in fact.'

Hydrogen sulphide is corrosive, foul-smelling, flammable and deadly in sufficient concentrations. A single breath can kill. Yet the gas has recently become a buzzword in scientific circles following discoveries that in tiny doses it plays a significant role in influencing some chemical pathways in the body.

'We are at the beginning of an expanding field that could have enormous clinical implications,' said David Lefer, cardiovascular physiologist at New York's Albert Einstein College of Medicine, in the journal Science last week.

One key piece of research has shown that hydrogen sulphide could protect against internal bleeding, ulcers and other gastric effects suffered by those on long-term regimes of anti-inflammatory painkillers such as aspirin and ibuprofen. In a series of experiments on rats and mice, Wallace and his colleagues found that these painkillers - when administered with chemicals that released hydrogen sulphide into the gut - produced no harmful side effects.

'Now we are preparing to repeat these experiments on humans,' said Wallace, who has formed a company, Antibe Therapeutics, to create drugs based on hydrogen sulphide technology. 'We envisage using standard medicines, mixed with hydrogen sulphide-releasing chemicals, as painkillers that will not cause internal bleeding to long-term users.'

Hydrogen sulphide research in medicine began three years ago when Dr Mark Roth, of the Fred Hutchinson Cancer Research Centre in Seattle, Washington, found that mice exposed to low levels of the gas passed out, their body temperatures dropped more than 20C and their metabolic rates plunged. Once the gas was switched off, they returned to normal. Now Roth is working on research aimed at reproducing the effect in humans, buying time for patients who have had heart attacks, strokes or wounds that have caused drastic losses of blood.

'I still get startled reactions from other scientists when I put forward proposals to use it for medical research,' said Wallace. '"Isn't this a poison?" they say to me. Then I point out what researchers have already found and they look stunned.'